1. Field of the Invention
The present invention relates to a measuring machine used for measuring the linearity, planeness or shape of an object.
The first invention relates to a noncontacting type measuring machine.
2. Description of the Prior Art
Conventionally, the noncontacting type measuring machine 30 (hereinafter referred to as a "measuring machine") used for measuring the linearity, the planeness or shapes has a cylindrical structure as shown in FIGS. 19 and 20, in which a cylinder 34 is divided into two pressurizing chambers by a sealing member 33 such as an O-ring provided on the outer wall face of a piston 31, and the lower pressurizing chamber 37 is linked to an inner hole 35a of an injection nozzle 35 mounted at the tip of a rod 32 projecting from the piston 31 via a tube 39, and there is an outer hole 35b formed on the outer periphery of said inner hole 35a. Furthermore, it has a structure that a needle-contacting portion 36a of an electric micrometer 36 is disposed at the back end of the rod 32, fixed to the cylinder 34 such that the needle-contacting portion 36a contacts with the end face of the rod 32.
In such a measuring machine 30, the air is supplied to the outer hole 35b of the injection nozzle 35 and injected from the tip of the injection nozzle 35 to the surface of the object 50 to be measured, and the back pressure from the object 50 to be measured is taken from the inner hole 35a of the injection nozzle 35 into the lower pressurizing chamber 37. If the pressure which is to be the reference pressure is preliminarily supplied to the upper pressurizing chamber 38, the piston 31 will stop at a position where the back pressure taken into the lower pressurizing chamber 37 and the reference pressure of the upper pressurizing chamber 38 are balanced. At this time, the injection nozzle 35 at the tip of the rod 32 is at rest in a state that it keeps a certain distance between the object 50 to be measured and itself. And if a value of an electric micrometer 36 disposed above the rod 32 has been detected as a reference value, when the measuring machine 30 is moved from side to side, the back pressure is increased/decreased along the surface shape of the object 50 to be measured, whereby the linearity and planeness of the object 50 to be measured can be measured without contacting with the object 50 to be measured, by moving the piston 31 vertically until the pressure in both pressurizing chambers 37 and 38 is balanced again, and detecting the displacement of the piston 31 with the electric micrometer 36.
In the structure of said measuring machine 30, however, since the sealing member 33 provided on the outer wall face of the piston 31 is press contacting with the cylinder 34, the actuation of the piston 31 is bad, and when the piston 31 moves, the followability of the piston 31 has been harmed as sliding resistance is always generated. Furthermore, since the temperature in the cylinder 34 increases due to the friction heat generated by the sliding resistance to expand the air which is a working medium, there may be a difference in the measured value and it is hardly said to be a measuring machine with high precision.
Furthermore, since the sealing member 33 is formed by an elastic body such as rubber, the frictional wear is severe, and there is also such a problem that it has to be changed in a short time.
Therefore, in order to solve the above problems, there has been proposed a measuring machine 40, as shown in FIG. 21, which is composed of an actuator hydrostatically supporting the piston 41 in the cylinder 44, an air micro-type nozzle 45 provided at the tip of the rod 42 projecting from said piston 41, a differential pressure gage 46, and a driving device 49 which moves the piston 41 by an electric signal from the differential pressure gage 46 (Japanese Unexamined Patent Publication No. Hei 4-43210).
In this measuring machine 40, the air supplied to the upper-stage chamber 45b of the two-stage throttled air micro-type nozzle 45 (hereinafter referred to as a "nozzle") is supplied to the lower-stage chamber 45a via an orifice 45c to be injected from the tip of the nozzle 45 to the object 50 to be measured, wherein the back pressure is taken into the lower-stage chamber 45a, the differential pressure with the reference pressure is detected by using a differential pressure gage 46 and the differential pressure is converted into an electric signal. And, when said electric signal is applied to a moving coil 49a (hereinafter referred to as a "coil") which constitutes the driving device 49, a magnetic field is formed between a magnet 49b inserted into the inside of the coil 49a and the coil 49a, and the coil 49a moves according to the Fleming's rule, whereby the nozzle 45 integrally formed with said coil 49a is always kept at a certain distance from the object 50 to be measured, the displacement of the nozzle 45 can be detected by monitoring the electric current sent to the coil 49a, and the surface conditions of the object 50 to be measured can be detected by the detected value. The reference numeral 51 represents bellows.
However, in the measuring machine 40 with the above structure, the influence due to the sliding resistance of the piston 41 could be dissolved, but there were the following problems.
First, the back pressure of the object 50 to be measured taken from the nozzle 45 was a very weak pressure, and even if this back pressure might be enputted directly to the differential pressure gage 46, a dead zone might be caused where the differential pressure with the reference pressure could not be detected with the precision of the current differential pressure gage, and minute unevenness on the surface of the object 50 to be measured could not be detected.
Furthermore, the differential pressure detected by the differential pressure gage 46 is converted to an electric signal to be applied to the coil 49a, but since the coil 49a generates heat due to the electric resistance of the coil 49a itself and is deformed through heat expansion, the magnetic flux density between the magnet 49b and the coil 49a is changed so that the linearity between the electric signal applied to the coil 49a and the moving volume of the piston 41 cannot be obtained, whereby there is a difference in the measured value.
Furthermore, though the coil 49a moves in the axial direction according to Fleming's rule, since the magnetic flux density is after all changed with the movement of the coil 49a, not only the linearity between the electric signal applied to the coil 49a and the moving volume of the piston 41 cannot be obtained, but also too much time is required to apply the differential pressure detected by the differential pressure gage 46 to the coil 49a to move the piston 41, whereby there was also a problem in the responding property.
Furthermore, the magnet 49b had to be disposed with high positional precision on the axis of the coil 49a, and therefore the attachment of the driving device 49 was very difficult.
The second invention relates to a noncontacting type measuring machine improved to make the structure simple.
The third invention relates to a contacting type measuring machine, more particularly relates to a noncontacting type measuring machine for measuring the object which is likely to be deformed and harmed.
Conventionally, both contacting type and noncontacting type measuring machines have been used for measuring shapes and thickness or the degree to which objects are parallel. Contacting type measuring machines have been used for measurements in which high resolution is required.
In the structure of the main part of this contacting type measuring machine, as shown in FIGS. 22(a) and (b), a probe 151 is attached such that it carries out a seesaw movement with a rotation bearing 152 as a center, and the tip of said probe 151 is formed in a spherical shape. The tip of the probe 151 is pushed to the object to be measured, and the deflection width of the probe 151 is to be detected when the object to be measured or the measuring machine 150 is moved.
Incidentally, these measuring machines 150 have a structure such that a pressure spring 153 is disposed opposite to a shock-absorbing damper 154 at the back end of the probe 151, in order to prevent damage and also prevent the tip of the probe 151 from disengaging the object to be measured.
Furthermore, in these measuring machines 150, there are two types according to the detection method. The measuring machine 150 shown in FIG. 22(a) is an electromagnetic induction type, wherein the deflection width of the probe 151 is detected as an impedence change of a coil 156 caused when a rod-like iron piece 155 mounted at the back end of the probe 151 goes in/out the coil 156 provided separately.
Furthermore, a measuring machine 150 shown in FIG. 22(b) is a photoelectric type, wherein the deflection width of the probe 151 is detected by detecting the number of the rod-like body 159 mounted at the back end of the probe 151 intercepting the photoelectric slit 160 by using a laser diode 157, a phototransistor 158 and the like, and converting the detected value into the change of respective height.
However, a problem exists with the contacting type measuring machine 150. Because the contact pressure with the object to be measured is large, objects which are easily deformed and damaged cannot be measured. For example, objects which cannot be measured include soft thick-film patterns before firing which are formed in, e.g., laminated chip condensers, IC packages and the like.
Namely, if the tip of the probe 151 of said contacting type measuring machine 150 is contacted with an object to be measured, the resultant forces of the weight of the probe 151, the sliding resistance within the bearing 152 and the elastic forces of the pressure spring 153 work as a contact pressure. And there has been a problem that if the object to be measured is a soft thick-film pattern before firing which is formed in said laminated chip condenser, IC package and the like, the contact pressure is so large that when a contacting type measuring machine 150 or an object to be measured is moved, the probe 151 shaves the surface of the thick film without deflecting to make the measurement impossible.
Furthermore, in the measurement of an object to be measured which is a little harder than said thick film, even if the deflection of the probe 151 can be detected, since the sliding resistance within the bearing 152 and the elastic force of the pressure spring 153 are changed by the deflection width of the probe 151, it has been difficult to measure with always constant contact pressure, and as the pressure spring 153 oscillates easily due to the external mechanical vibration, the obtained measurement result has had a low reliability.
Therefore, in order to reduce the contact pressure with the object to be measured, various contrivances such as material changes and design changes have been tried. However, with the current contacting type measuring machine 150 composed of such members as a probe 151, a bearing 152, a pressure spring 153 and a shock-absorbing damper 154, it has been difficult to reduce the contacting pressure due to the weight and resistance of their own, and it has been impossible to measure an object which is likely to be deformed and damaged.
Furthermore, there have been problems such that these pressure springs 153 and shock-absorbing dampers 154 are weak in impact load, and undergo age changing in a short period of time, and particularly, the reproductivity after repetitively measured is degraded due to the backlash of compression/expansion.
The object of the third invention is to provide a contacting type measuring machine which makes the measurement with high precision possible without causing any deformation or damages for an object which is soft and likely to be deformed or damaged as mentioned above.
The fourth invention relates to a measuring machine having a pressure amplifier for amplifying a pressure signal inputted to the noncontacting type measuring machine of a gas injection style.
A noncontacting type measuring machine 230 which injects air (hereinafter referred to as a "measuring machine") as shown in FIG. 23 has been conventionally used. In this measuring machine 230, a pressure which is to be a reference pressure is supplied to the upper pressurizing chamber 237 which is one of the two pressurizing chambers formed in a cylinder 234 on both sides of a piston 231, and the other lower pressurizing chamber 236 is connected with a hole 222 of an injection nozzle 220 (hereinafter referred to a "nozzle") mounted to a rod 232 projecting from the piston 231, via a tube 240. In addition, another hole 223 is provided on the outer periphery of the hole 222 in the nozzle 220, and is linked to a gas supply opening 221. On the other hand, in order to measure the displacement of the piston 231, a needle-contacting portion 235a of a micrometer 235 is mounted to the cylinder 234 so that it always contacts with the upper end face of said piston rod 232.
Therefore, when the air is supplied to the gas supply opening 221 of the nozzle 220 to be injected from the hole 223 of the nozzle 220, the back pressure according to the distance between the object to be measured 225 and the nozzle 220 is taken from the hole 222 of the nozzle 220 into the lower pressurizing chamber 236. When the object to be measured 225 is drawn near to the nozzle 220, said back pressure becomes larger, and at a certain position, the reference pressure of the upper pressurizing chamber 237 and the back pressure of the lower pressurizing chamber 236 are balanced, the piston 231 stops in the cylinder 234 to keep the nozzle 220 at a certain distance with the object to be measured 225. At this time, by measuring the value of the micrometer 235, the measurement preparation is completed.
Then, when said measuring machine 230 is moved horizontally against the object to be measured 225, the back pressure is changed corresponding to the surface shape of the object to be measured 225. As a result, the piston 231 moves, and by measuring the displacement of the piston 231 with the micrometer 235, the surface shape of the object to be measured 225 can be measured.
However, in the case where the surface shape of the object to be measured 225 is delicately changed, there is a case that the back pressure cannot be detected because of being a minute pressure. Therefore, a pressure amplifier 211 as shown in FIG. 24 has been used at the tip portion of the nozzle 220 so that the back pressure can be detected even if being a minute pressure (see Japanese Unexamined Patent Publication No. Sho 58-56405).
In this pressure amplifier 211, a diaphragm 212 formed with a polyethylene film, stainless thin plate and the like is provided in a cylinder body 213, and an input chamber 216 and an output chamber 217 are provided on the both sides of said diaphragm 212. And in the input chamber 216, an injection hole 215 in the axial direction, and a supply hole 214 in the horizontal direction project respectively, and the output chamber 217 is connected with the injection nozzle 220 of a noncontacting type measuring machine 230 with a clearance 218 by bolting and the like.
And while operating the measuring machine 230 as described above, pressure is supplied from the supply hole 214 of the pressure amplifier 211 to inject the air from the injection hole 215, then the back pressure from the object to be measured 225 can be taken into the input chamber 216 and this back pressure can be amplified and transmitted to the output chamber 217 via the diaphragm 212. Namely, if the pressure (the back pressure from the object to be measured 225) input to the input chamber 216 is assumed to be Pi, the pressure injected from the hole 223 of the nozzle 220 is assumed to be Pn, the effective area of the diaphragm 212 is assumed to be Ai, and the effective area of the hole 223 of the nozzle 220 is assumed to be An, the diaphragm 212 is stopped in a state that the force Pi.Ai on the side of the input chamber 216 and the force Pn.An on the side of the output chamber 217 applied to the diaphragm 212 are balanced. At this time, the following equation is realized: EQU Pn=(Ai/An).times.Pi
Then, the pressure Pi input from the injection hole 215 is increased or decreased by .delta.Pi, the increase or decrease .delta.Pn of the pressure Pn input to the nozzle 220 will be Ai/An.multidot..delta.Pi and can be taken out amplified by Ai/An times from the above equation, and in the end, the pressire signal can be amplified and taken out by the ratio of the effective area Ai of the diaphragm 212 to the effective area An of the hole 223 of the nozzle 220.
However, there has been a problem shown as follows in the conventional pressure amplifier 211.
In the pressure amplifier 211 having a diaphragm 212 formed with a polyethylene film, since the polyethylene film itself has a large flexibility, there has been a problem that the diaphragm 212 is displaced partially with the pressure change input to the input chamber 216, and a hysteresis is caused in the pressure signal transmitted to the output chamber 217.
Therefore, if a pressure amplifier 211 having a diaphragm 212 formed with a metal plate such as a stainless thin plate is used, though the hysteresis becomes few compared to that of the diaphragm 212 composed of a polyethylene film, conversely there has been a problem that the dynamic resistance becomes large, and a difference is caused in the pressure signal transmitted to the hole 222 of the nozzle 220.
Furthermore, in the conventional pressure amplifier 211, the dynamic resistance differs due to the materials and thickness of the diaphragm 212, and the range which can be amplified has been limited. Therefore, plenty of pressure amplifiers 211 according to the pressure range to be inputted have to be prepared.
Furthermore, the diaphragm 212 made of a metal is likely to be broken in a short time due to the fatigue by repetition of sliding and bending, and the decrease of the life due to the changing with time is fast, whereby the diaphragm could not have been used for a long time. And, there have been various problems that have caused rust and corrosion in the diaphragm 212 in an environment containing much moisture and an environment containing specific gases, and much care should be taken in the measurement atmosphere and storing places.